The present invention relates generally to micro-electro-mechanical-system (MEMS) devices. More particularly, the present invention relates to actuators for MEMS mirror devices. Specifically, the present invention relates to shaped electrodes for MEMS devices to improve actuator performance and methods for fabricating the same.
A MEMS device is a micro-sized mechanical structure having electrical circuitry fabricated using conventional integrated circuit (IC) fabrication methods. One type of MEMS device is a microscopic gimbaled mirror device. A gimbaled mirror device includes a mirror component, which is suspended off a substrate, and is able to pivot about a gimbal due to electrostatic actuation. Electrostatic actuation creates an electric field that causes the mirror component to pivot. By allowing the mirror component to pivot, the mirror component is capable of having an angular range of motion in which the mirror component can redirect light beams to varying positions.
One type of electrostatic actuator for a gimbaled mirror device is parallel plate actuator. A parallel plate actuator uses planar electrodes formed on a planar surface of a substrate below a suspended mirror component. A voltage is applied to the planar electrodes that create an electric field to cause the mirror component to move.
A disadvantage with the parallel plate actuator for a gimbaled mirror is that the force required to move the mirror component is directly proportional to the square of the distance of the gap between the planar surface of the electrodes, which is substantially at the surface of the substrate, and the mirror component. As such, to obtain a large range of angular motion, the mirror component must be suspended at a large height above the electrodes. In such a configuration, a large amount of voltage is necessary to produce force for actuation.
A further disadvantage of using the parallel plate actuator is that it is difficult to shape the electric field. That is, the shape of the electric field for actuation is limited by the dimensions of only the top surface of the planar electrodes. Furthermore, the wiring necessary to connect the planar electrodes to a high voltage source for electrostatic actuation can cause interference (i.e., cross-talk) with neighboring mirror devices.
Another type of electrostatic actuator for a MEMS device is a comb-drive actuator. Prior combed finger actuators use a set of interdigitated fingers to move another set of interdigitated fingers. A disadvantage with prior comb-drive actuators is that it requires moving the xe2x80x9cmassxe2x80x9d of the moveable interdigitated fingers. Thus, to use a comb-drive actuator for a MEMS device, a large amount of power is required. Another disadvantage of using a comb-drive actuator is that it requires complex fabrication processes.
Shaped electrodes for MEMS devices to improve actuator performance and methods for fabricating the same are disclosed. A micro-electro-mechanical-system (MEMS) device is disclosed. The MEMS device includes one or more mirror devices and one or more shaped electrodes. Each shaped electrode is to provide an electric field for electrostatic actuation to move one of the mirror devices. Each shaped electrode is to shape the electric field based on a three dimensional geometry of the shaped electrode.
A method of fabricating a MEMS device is disclosed. A pillar wafer is attached to an electrode wafer. One or more pillars are formed from the pillar wafer. Furthermore, one or more gimbaled mirror devices can be formed on the electrode wafer such that the pillars are to provide an electric field or to provide a barrier for the mirror devices.
Another method of fabricating a MEMS device is disclosed. A first substrate having a metal contact is attached to a second substrate having an electrode. The metal contact is connected with the electrode. One or more pillars are formed from the first substrate. Furthermore, one or more gimbaled mirror devices can be formed on the second substrate such that the pillars are to provide an electric field or to provide a barrier for the mirror devices.
Another method of fabricating a MEMS device is disclosed. A plurality of trenches is formed in a first side of a substrate. An insulator is formed in the plurality of trenches and on the first side of the substrate such that the insulator defines exposed areas of the first side of the substrate. A metal line is formed on the insulator and exposed areas of the first side of the substrate. Portions of a second side of the substrate are removed selectively to form pillars connected with the insulator and the metal line. Furthermore, one or more gimbaled mirror devices can be formed on the substrate such that the pillars are to provide an electric field or to provide a barrier for the mirror devices.
Other features and advantages of the present invention will be apparent from the accompanying drawings, and from the detailed description, which follows below.